1. Technical Field
The present invention pertains to surgical cutting instruments for use in ophthalmic surgery and, more particularly, to such surgical cutting instruments designed to be economically disposable.
2. Discussion of the Prior Art
Many ophthalmic surgeons presently use surgical cutting instruments for cutting and removing vitreous, blood clots, cataracts, lenses and other matter from the eye. Such surgical cutting instruments use various means to cut or separate the matter from the eye including pulsating fluid jets or mechanical cutting or shearing mechanisms, such as rotating members or reciprocating members, the latter being exemplified by U.S. Pat. No. 3,776,238 to Peyman et al, U.S. Pat. No. 3,884,238 to O'Malley et al, U.S. Pat. No. 3,994,297 to Kopf, U.S. Pat. No. 4,011,869 to Seiler, Jr., U.S. Pat. No. 4,246,902 to Martinez and U.S. Pat. No. 4,314,560 to Helfgott et al. While such surgical cutting instruments have been well received and are commonly used in ophthalmic surgery, there is a need for an economically disposable surgical cutting instrument that can be available along with other instruments and materials required for surgery, particularly cataract surgery, in a sterilized package or kit. However, any economically disposable surgical cutting instrument must still provide precise cutting and adequate suction and evacuation of cut material and must be designed and shaped to facilitate manipulation by a surgeon. The above mentioned patents disclose surgical cutting instruments with a tubular outer member having a tubular inner member sliding therein and reciprocated by various means of motive power. These instruments have the disadvantages of not being economically disposable in that they include a number of intricate parts, require precision machining and tooling, requiring complicated assembly procedures, and requiring disassembly for sharpening and sterilization.
The surgical cutting instrument of U.S. Pat. No. 4,577,629 to Martinez has been well accepted as an economically disposable surgical cutting instrument for use in ophthalmic surgery while providing precision cutting and sufficient evacuation of cut material; however, alignment of the distal ends of the inner and outer probe members, which is crucial to proper precision cutting action, requires rotation of the piston via a tool engaging a slot in the piston prior to screwing the rear plug into the body. This alignment step increases the cost of assembly and continued alignment is dependent upon frictional engagement of the piston and seals with the body thereby requiring careful handling and close inspection during use to assure that alignment is maintained and misalignment does not occur inadvertently.